Fluid diaphragm pumps are known. Typically, diaphragm pumps must be shifted pneumatically using signals generated by a pilot valve which, in turn, shifts a ain air valve which thereafter directs the compressed air that powers the pump into the appropriate chamber. Thus, the combination of the air pressure, the pilot valve and the main air valve control the timing of the pump.
Other designs incorporate an external signal to shift the pump. Typically, these designs involve the use of a timer or a timer incorporated into a controller or processor. However, timers have been found to be problematic because the timing imposed by the timer may not correspond exactly with the timing of the pump. For example, if the timed interval provided by the timer is too short, the pump will not go through a full stroke. Conversely, if the timing interval provided by the timer is too long, the pump will cycle but will not pump at full displacement or at a high efficiency. In some cases, the pump will not pump at all. Further, there is no current system which provides feedback to the operator when the timer has been set to a time interval that is either too short or too long, i.e. an interval that does not result ir the pump displacing full strokes.
However, the use of external electric signal to shift a diaphragm pump would be advantageous because the shifting of the pump could be monitored by a control system and knowledge of the shifting rate is useful information for operation of both the pump and the overall system in which the pump is incorporated.
Further, because of the large number of fluid powered diaphragm pumps currently in use, it would be very advantageous to provide an electric shifting mechanism which could be incorporated into existing fluid power diaphragm pumps. Preferably, the same pilot valves and main air valves could be used with a new electric shifting mechanism.
Accordingly, there is a need for an electric shifting mechanism for fluid power diaphragm pumps. Further, there is a need for an electric shifting mechanism for fluid power diaphragm pumps which could be incorporated into existing fluid power diaphragm pumps or provided in the form of a retrofit kit. Still further, there is a need for an electric shifting mechanism for diaphragm pumps which could be easily incorporated into a control system for easily monitoring the operation of the pump.